An apparatus for constructing trellis systems, particularly for fruit vines. An apparatus may include a vertical post with a slot for slidably receiving a horizontal crossarm. In certain embodiments, an apparatus may include a vertical post, a horizontal crossarm, and a pair of diagonal crossarms. A vertical post may have slots for slidably receiving a horizontal crossarm and diagonal crossarms. A horizontal crossarm may also have slots for slidably receiving diagonal crossarms. Wire notches may be formed into a vertical post, horizontal crossarm, and/or a diagonal crossarm for attachment to a second apparatus or another stationary object, or for anchoring an apparatus to the ground. The present invention allows for a trellis system which is quickly and easily assembled, and highly durable.